Demonstrate understanding the properties of selected organic compounds (4 credits)
STRUCTURAL FORMULA
NCEA PAST EXAM QUESTION: Draw the structural formula (aka displayed or expanded structural formula) for the following organic substances
The table below provides an overview of the names of the organic substance and year that they appeared in the NCEA Exam paper
Additional questions on structural formula
The organic compound, 4-chloro-3-methylpent-4-ene has been named incorrectly. Draw the implied structure and explain why it is named incorrectly. The correct IUPAC name for this structure is:
Draw the structural formula for every organic substance named in the table above, you may find it useful to print the questions where there is space provided to draw the diagrams. Also, name the homologous series that the substance is in.
After completing the structural formulas to the best of your ability, look at the answers and correct the diagrams yourself.
Print a table of questions on structural formula that have not yet appeared in the NCEA Exams... complete the table and mark it yourself using the answers provided.
Print a table of questions on IUPAC naming that have not yet appeared in the NCEA Exams... complete the table and mark it yourself using the answers provided.
NCEA PAST EXAM QUESTIONS on structural and geometric isomers
(i) Define the term constitutional (structural) isomer.
(ii) Explain why 1,1-dichloroethene cannot exist as a cis-trans isomer.
(iii) A structural isomer of 1,1-dichloroethene canexist as cis-trans isomers. Draw and name the cis-trans isomers.
The structures of three organic compounds are shown below.
Explain why compound A can exist as geometric (cis and trans) isomers, but compounds B and C cannot. In your answer you should:
• draw the geometric (cis and trans) isomers of compound A in the boxes below
• explain the requirements for geometric (cis and trans) isomers by referring to compounds A, B, and C.
(a) Identify two molecules from the table in (a) that are constitutional (structural) isomers of each other. Justify your choice.
(b) Molecule D can exist as geometric (cis and trans) isomers.
(i) Draw the geometric (cis and trans) isomers for molecule D
(ii) Justify why molecule D can exist as geometric (cis and trans) isomers. Your answer should include:
• an explanation of the requirements for cis and trans isomers
• reference to the structure of molecule D.
1) Four of the structural isomers of C4H10O are alcohols. Draw each of these showing their structural formulae and IUPAC (systematic) names.
2) Can but-1-ene exist as geometric (cis-trans) isomers? Justify your answer, including reference to the requirements for geometric (cis-trans) isomers.
(a) Draw the TWO structural isomers of C2H2Cl2 AND name the isomers.
(b) One of the structural isomers from (b) can exist as geometric isomers (cis-trans).
i) Name the isomer that can exist as geometric isomers.
ii) Draw the geometric isomers of this molecule in the table below.
(c) Discuss why the organic molecule C2H4Cl2 forms structural isomers but does not form geometric isomers whereas the molecule C2H2Cl2 forms both structural AND geometric isomers.
In your answer, you must include:
a description of each type of isomer (geometric or structural)
the characteristics of molecules that form these types of isomer
the structural formulae and functional groups of both C2H4Cl2 AND C2H2Cl2.
i) Only Molecule C can exist as geometric (cis-trans) isomers. Draw the geometric (cis-trans) isomers of Molecule C.
ii) Discuss why Molecule C can exist as geometric (cis-trans) isomers but Molecule A and Molecule B cannot exist as geometric isomers.
In your answer you must include an explanation of what a geometric isomer is.
(a) Identify TWO molecules that are structural isomers of each other using the bold letters from the table above.
(b) i)Identify ONE molecule that can exist as geometric (cis–trans) isomers using the bold letter from the table above.
ii) Draw the cis and trans isomers for your chosen molecule in the boxes below.
iii) Discuss why the molecule you have selected can exist as cis–trans isomers.
Your answer must include:
• an explanation of why cis–trans isomers can exist
• reference to the structure of the selected molecule
(a) i) Draw ALL the structural isomers of alkenes of molecular formula C4H8
ii) One of the isomers of C4H8 can be oxidised with potassium permanganate, KMnO4, to form 2-methyl propan-1,2-diol.
Four different molecules with the molecular formula C5H10 are given below.
(a) Describe why these molecules are structural isomers.
(b) One of the molecules shown above may exist as cis-trans isomers.
i) Identify this molecule using the bold letter from the above table.
ii) Draw the cis and trans isomers of the molecule identified in (i).
(c) Discuss why the molecule you selected in (b) i) may exist as cis-trans isomers, while the other three isomers cannot
Consider the following compounds.
(a) Which compounds are structural isomers? Identify using the bold letters designating the molecules.
(b) Explain why the compounds you have selected are structural isomers.
and
Structural isomers of the molecular formula C2H2Cl2 are 1,1–dichloroethene and 1,2–dichloroethene.
(a) Circle the compound that can exist as cis-trans isomers: 1,1–dichloroethene or 1,2–dichloroethene
(b) Draw the cis and trans isomers of the compound you circled in (a).
(c) Discuss the requirements for cis-trans isomerism. In your answer include reasons explaining why the structural isomer you selected above can exist as cis-trans isomers while the other structural isomer cannot.
Two alkenes, but–1–ene and but–2–ene, are structural isomers of the compound with the molecular formula, C4H8
(a) Draw and name another structural isomer of the compound, C4H8.
(b) But–2–ene can exist as geometric (cis–trans) isomers, whereas but–1–ene cannot. Explain this difference.
NCEA PAST EXAM QUESTIONS ON Polymerisation of alkenes
Cling Wrap is a polymer that can be made from the monomer 1,1-dichloroethene. Draw THREE repeating units of the polymer formed.
i) Draw TWO repeating units of the polymer formed in reaction 5
ii) Compare and contrast the polymer formed in reaction 5 to the polymer formed in the first reaction. In your answer you should explain why the polymers formed in these two reactions are different.
i)The molecule tetrafluoroethene, shown below, is the monomer for the polymer commonly known as Teflon.
CF2=CF2
Draw TWO repeating units for the Teflon polymer.
ii) The following diagram shows three repeating sections of another polymer.
Draw two repeating units of the polymer formed from but-1-ene
and
The following diagram shows four repeating sections of the polymer commonly called polypropene. Draw the structural formula of the monomer molecule used to make this polymer.
The molecule undergoes an addition polymerisation reaction to form a polymer. Draw THREE repeating units for the polymer made from this molecule.
But-2-ene, CH3–CH=CH–CH3, undergoes an addition polymerisation reaction to form a polymer. Draw THREE repeating units for the polymer.
(a) i) The following diagram shows three repeating sections of a common polymer. Draw the structural formula of the monomer molecule used to make this polymer.
ii) The molecule 2-methyl propenoate, shown below, is the monomer for the polymer commonly known as Perspex. Draw the structural formula of the polymer Perspex showing TWO repeating units.
The following diagram shows four repeating sections of the polymer commonly known as PVC. Draw the structural formula for the monomer molecule used to make this polymer.
Complete the table below by drawing the structural formula of the monomer or polymer (showing two repeating units).
Two common polymers are polypropylene and polyvinyl chloride (PVC). A section of each polymer is shown in the table below. Draw the structural formula for the monomer molecule for each polymer.
iii) Describe the type of reaction occurring and explain why it is classified as this type of reaction
Chloroethane, CH3CH2Cl, reacts with aqueous KOH, alcoholic KOH, and with NH3. Compare and contrast the reactions of chloroethane with the three reagents.
In your answer you should include:
• the type of reaction occurring and the reason why it is classified as that type
• the type of functional group formed
• equations showing structural formulae for reactions occurring.
NCEA PAST EXAM QUESTIONS on primary, secondary and tertiary haloalkanes and alcohols
Draw a primary, a secondary, and a tertiary alcohol for the molecule C5H11OH.
Molecule 1 below can be classified as a tertiary alcohol. Molecule 2 can be classified as a tertiary haloalkane.
(a) Describe why both these molecules can be classified as tertiary.
(b) Explain why Molecule 1 and Molecule 2 are not structural isomers of each other. In your answer, you should outline what a structural isomer is, and refer to both molecules.
(c) Draw a structural isomer of Molecule 1
Classify each of the following alcohols as primary, secondary or tertiary and explain your answer for each substance
Vitamin C has the following structure. Classify the –OH groups labelled A and B as primary, secondary or tertiary.
Four alcohols with the same molecular formula are shown in the table below. Complete the table by classifying each alcohol as primary, secondary or tertiary.
Vitamin C has the structure shown below
(a) On the molecule circle the section that is an alkene and would readily react to decolourise bromine water.
(b) Two of the -OH groups in the molecule have been labelled as (A) and (B). Classify these -OH groups as primary, secondary or tertiary alcohol groups.
NCEA PAST EXAM QUESTIONS on tests to identify organic substances
Four separate colourless organic liquids are known to be:
• ethanol
• ethanoic acid
• hex-2-ene
• hexan-1-amine (1-aminohexane).
Write a procedure to identify each of these organic liquids using only the reagents listed below.
• acidified dichromate solution, Cr2O72– / H+(aq)
• bromine water, Br2(aq)
• sodium carbonate solution, Na2CO3(aq).
In your answer, you should:
• identify the test reagents used
• describe any observations that would be made
• identify the type of reaction that occurs
• identify the organic product of any reaction.
You do not need to include equations in your answer.
Five separate colourless organic liquids are known to be:
• pentan-1-ol
• ethanol
• pent-1-ene
• pentane
• ethanamine.
Write a valid method to show how each of these liquids can be identified using only water, litmus paper, and bromine water, Br2(aq).
Your method should allow another student to identify these liquids, and include:
• the reagent used
• any observations made.
You do not need to include equations in your answer.
1) Two bottles containing pent-1-ene, CH3CH2CH2CH=CH2, and hexane, CH3CH2CH2CH2CH2CH3, require identification.
Two reagents, bromine water, Br2, and acidified potassium permanganate, MnO4– / H+, are available.
Evaluate the possible use of BOTH reagents to distinguish between the pent-1-ene and hexane.
In your answer you should include:
• a description of the type of reactions that would occur
• any conditions that would be required
• any observations that would be made
• equations showing the structural formulae of the organic reactant(s) and product(s).
2) State how you could distinguish between aminobutane, CH3CH2CH2CH2NH2, and butanoic acid, CH3CH2CH2COOH, using damp litmus paper.
Give a reason for your answer.
(a) Five colourless organic solutions that have no labels on the their bottles are known to be:
ethanoic acid
aminoethane
ethanol
hexane
hex-1-ene.
Discuss how each of these samples can be identified using only water, red and blue litmus paper, and bromine water.
In your answer, you must include a coherent scheme that would allow another student to follow your method, along with:
the reagent used
observations
chemical equations that show the species reacting and products formed.
Samples of hexane, hex-1-ene and propanoic acid, require identification.
Only two reagents are available: acidified potassium permanganate solution, MnO4– / H+, and sodium carbonate solution, Na2CO3.
Discuss how each of the three samples can be identified using only the reagents above.
Your answer must include:
• a clear description of what you would do
• reagent used
• observations
• equations showing the structural formulae of organic reactant(s) and product(s).
The following substances require identification:
• acidified potassium dichromate
• bromine water
• methanol
• hexane
• hex-1-ene.
Two of these substances are orange in colour, the other three are colourless.
Discuss, using only the five substances, how each could be identified.
Your answer should include:
• a clear description of what you would do
• observations
• equations showing the structural formulae of organic substances for any reactions occurring.
Samples of 1-hexene and ethanoic acid require identification.
Two reagents are available: bromine water and zinc metal.
Discuss the reaction of these two samples with the reagents above.
Your answer must include:
• the reagent used
• observations
• equations showing the structural formulae for any reactions occurring.
Three colourless organic liquids have no labels on the bottles. They are known to be pentanoic acid, pentan–1–ol and pent–1–ene.
(a) Draw structural formulae for these three substances.
Using only aqueous solutions of bromine and potassium permanganate, discuss how a student could identify the liquids.
Your answer should include:
• what is done
• related observations
• conclusions made
• organic products for any reactions occurring.
a) (i) Identify a chemical test to distinguish between propanoic acid and propan-1-ol.
(ii) Describe the test to be carried out and the expected observations for each compound.
(b) The structural formulae for two compounds are given below:
CH3–CH2–CH2–CH2–CH2–CH3 CH2=CH–CH2–CH2–CH2–CH3
hexane hex–1–ene
Both compounds will react with bromine (Br2), but under different conditions. Discuss how the reactions with bromine could be used to distinguish between hexane and hex–1–ene.
In your answer include a description of expected observations, the conditions necessary for a reaction to occur, the type of reaction occurring and explanation for this, relevant equations and names of any products formed.
Chemical tests can be used to distinguish between pairs of compounds. Identify tests to distinguish between butan-1-ol and but-2-ene and
(i) describe the test to be carried out,
(ii) describe the expected observations for the test used,
(iii) clearly explain how the test results can be used to distinguish between them and why the test used is a suitable one.
1) The reactions shown below are all classified as being the same type of reaction.
Compare and contrast these reactions. In your answer you should:
• state whether any conditions are required
• describe the type of reaction occurring and explain why all three reactions are classified as this type of reaction
• explain why two layers form in Reaction One.
2) Sodium carbonate, hydrochloric acid, and sulfuric acid are each added to separate samples of three organic compounds.
The structures of the compounds and the products of any reactions are given in the table below.
Compare and contrast the reactions that do occur between these organic compounds, and the reagents in the table above.
In your answer you should:
• give the structure of the organic products (i) and (ii)
• describe the different types of reactions occurring, and give reasons why they are classified as that type
• identify any specific conditions that are required for the reactions to occur.
3) i)Explain why the reaction shown below, is classified as an elimination reaction.
ii) The reaction belowis also an elimination reaction. Draw the structural formula of the product formed
1) Butan-1-ol can react separately with each of PCl5, Cr2O72–/ H+, and concentrated H2SO4.
For each reaction, your answer should include: the type of reaction occurring and the reason why it is classified as that type
Chloroethane, CH3CH2Cl, reacts with aqueous KOH, alcoholic KOH, and with NH3. Compare and contrast the reactions of chloroethane with the three reagents. In your answer you should include:
• the type of reaction occurring and the reason why it is classified as that type
• the type of functional group formed
• equations showing structural formulae for reactions occurring.
i) The types of reactions below can be described as addition, elimination, or substitution reactions.
Allocate these reaction types to each of the four reactions
1)
CH3–CH2–CH2–OH --> C3H7Cl
Reaction type:
2)
C3H7Cl --> CH3–CH2–CH2–NH2
Reaction type:
3)
CH3–CH2–CH2–OH --> C3H6
Reaction type:
4)
C3H6 --> C3H7Cl
Reaction type:
ii) Compare and contrast the similarities and differences between addition, elimination, and substitution reactions. You should use the examples of the reactions above in your answer
For the following reaction
• Write the structural formula of the organic product formed.
• elimination or addition or oxidation or substitution or hydrolysis or halogenation or acid-base
1) For each of the THREE following reactions:
• Write the name or structural formula of the reactant used.
• State the type of reaction occurring. Choose from acid-base or addition or elimination or hydrolysis or substitution
i)
ii)
iii)
2) Hydrocarbons can undergo addition and substitution reactions. Compare and contrast addition and substitution reactions. Use the reactions of ethane, CH3– CH3, and ethene, CH2= CH2, with chlorine as your examples in your answer.
Your answer must also include:
• a description of each type of reaction
• conditions for addition and substitution reactions
• equations showing the structural formulae of the organic reactant(s) and product(s).
1) (i) Write the IUPAC name or the structural formula of the product formed.
(ii) State the type of reaction occurring. Choose from the following words: acid-base or addition or elimination or hydrolysis or oxidation or polymerisation or substitution
(a) Ethanol is heated with a catalyst (either concentrated sulfuric acid or aluminium oxide).
(b) Propanoic acid is reacted with sodium hydroxide solution.
(c) Propene is reacted with hydrogen in the presence of a nickel catalyst at 150°C.
2) Compare and contrast the reactions of ethene and ethanol with acidified potassium permanganate. For each reaction you must include:
• observations
• equations showing the structural formulae of the organic reactant and product
• type of reaction occurring.
Some reactions involving organic compounds can be classified as addition or elimination. Use the examples (a) and (b) given below to clearly explain the type of reaction involved:
(i) complete the equation to show the main organic product formed
(ii) use the example to explain why it is classified as that type of reaction.
(a) When HCl reacts with but–1–ene an addition reaction occurs.
(b) When ethanol is heated with concentrated sulphuric acid an elimination reaction occurs.
NCEA EXAM QUESTIONS on mostly one step organic reactions
1.
In Reaction 1, propan-2-ol can be converted to propeneIn Reaction 2, propene can be converted back to propan-2-ol.
Analyse BOTH of these reactions by:
describing the reagents and conditions needed for each reaction to occur
identifying each type of reaction and explaining your choice
2.
Ethene, C2H4(g), reacts with aqueous potassium permanganate solution, KMnO4(aq), dilute acid, H2O / H+, and hydrogen bromide, HBr.
Compare and contrast the reactions of ethene gas with each of these three reagents. In your answer, you should: • describe any observations that can be made • identify, with reasons, the type of reaction ethene undergoes with each reagent • describe the functional group of the products formed • include equations showing the structural formulae for the organic compounds for each reaction.
i) When primary alcohols are oxidised by acidified permanganate, MnO4–/ H+, they form carboxylic acids. Draw the primary alcohol that was oxidised to form the carboxylic acid shown.
ii) Permanganate ion, MnO4–, can be used to oxidise alkenes. Draw the product of the following reaction:
Butan-1-ol can be oxidised to form a carboxylic acid.
i) Write the name or formula of a suitable reagent that could be used to carry out the reaction. Include any specific conditions.
ii) Describe the colour change that would be observed.
iii) One of the other alcohol isomers of C4H10O can also be oxidised to form a carboxylic acid. Identify this isomer by name or structural formula: Explain your choice of isomer.
Give the structural formula of the organic product formed when:
(i) Ethanol, C2H5OH, reacts with acidified potassium dichromate solution.
(ii) Ethanoic acid, CH3COOH, reacts with sodium carbonate solution.
(iii) One of the isomers of C4H8 can be oxidised with potassium permanganate, KMnO4, to form 2-methylpropan-1,2-diol. Complete the following equation to show the structural formula of the isomer of C4H8
(iv) 2-methyl propan-1,2-diol can be further oxidised with acidified potassium dichromate, Cr2O72– / H+, to form a compound with molecular formula C4H8O3. The compound C4H8O3 reacts with sodium carbonate solution to form bubbles of carbon dioxide gas. Draw the structural formula of the compound C4H8O3.
1) Complete the following reactions by writing the structural formula of each organic product.
i)
ii) iii) 2) Methylpropene can be formed from methylpropan–2–ol. Identify a reagent that can be used to do this.
Complete the following equations by drawing the structural formula of the organic products in the boxes provided.
i) ii)
b) Reaction (ii)above can also be carried out using one of the reagents shown: H2 / Ptconc. H2SO4 MnO4– / H+
(i) Circle the correct reagent.
(ii) Describe what would be observed when this reaction occurs.
Print out these flowcharts onto paper and stick onto your study wall or toilet door, you need a really clear picture in your head of these reactions. Even better....write and draw out your own flowchart summary.
(i) Complete the scheme above by drawing the structural formulae of the organic compounds A to D.
(ii) Circle the functional group of each of the organic compounds A, B, and C that you have drawn.
(iii) Identify reagents X and Y.
The reactions shown below are all classified as being the same type of reaction.
Compare and contrast these reactions. In your answer you should:
• state whether any conditions are required
• describe the type of reaction occurring and explain why all three reactions are classified as this type
• explain why two layers form in Reaction One.
1) The flow diagram below shows a reaction scheme for the conversion of but-1-ene into but-2-ene.
Use the reaction scheme above to write down:
• the formula of each reagent, including any necessary conditions
• the type of reaction occurring.
2) Butan-1-ol can react separately with each of PCl5, Cr2O72–/ H+, and concentrated H2SO4.
Elaborate on the reactions of butan-1-ol with each of the three reagents.
For each reaction, your answer should include:
• the type of reaction occurring and the reason why it is classified as that type
• the name of the functional group formed in each product
• the structural formula of the organic product.
But-1-ene is used in the reaction sequence shown below.
(i) Draw two repeating units of the polymer, B, formed in Reaction 1.
(ii) Give the name or formula of a suitable reagent in Reaction 4; include any specific conditions required.
(iii) Give the name or formula of a suitable reagent in Reaction 3; include any specific conditions required.
(a) The flow diagram below shows some reactions involving organic substances.
Compound A has a molecular formula C3H8O. It reacts readily with acidified potassium dichromate solution,
(i) Write the structural formula of Compound A.
(ii) Write the structural formulae for Compound B
(iii) Write the name OR formula of Reactant P, Reactant Q, and Reactant R. State any conditions for the reaction to occur
The flow diagram below shows a series of organic reactions.
Complete the diagram by drawing structural formulae and writing IUPAC (systematic) names for the compounds A, B and C (which turns litmus red) and identifying reagent D
An unsaturated compound A, C3H6, reacts with water under acidic conditions to form two new products, B and C. Product B reacts with acidified potassium dichromate solution to form D. Product D reacts with a solution of sodium carbonate producing bubbles of gas.
Write down the structural formula and name for each compound A, B, C and D
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The types of reactions in the flow diagram on the opposite page can be described as addition, elimination, or substitution reactions.(i) Allocate these reaction types to each of the four reactions occurring in the flow diagram on the opposite page. and contrast the similarities and differences between addition, elimination, and substitution reactions. You should use the examples of the reactions from (c) (i) in your answer.
STRUCTURAL FORMULA
NCEA PAST EXAM QUESTION: Draw the structural formula (aka displayed or expanded structural formula) for the following organic substances
The table below provides an overview of the names of the organic substance and year that they appeared in the NCEA Exam paper
Additional questions on structural formula
The organic compound, 4-chloro-3-methylpent-4-ene has been named incorrectly. Draw the implied structure and explain why it is named incorrectly. The correct IUPAC name for this structure is:
Draw the structural formula for every organic substance named in the table above, you may find it useful to print the questions where there is space provided to draw the diagrams. Also, name the homologous series that the substance is in.
After completing the structural formulas to the best of your ability, look at the answers and correct the diagrams yourself.
Print a table of questions on structural formula that have not yet appeared in the NCEA Exams... complete the table and mark it yourself using the answers provided.
IUPAC NAMING
NCEA PAST EXAM QUESTION: Write the IUPAC (systematic) names for the following organic substances
The tables below provide an overview of the molecules and year that they appeared in the NCEA Exam paper
ADDITIONAL NCEA PAST EXAM QUESTIONS on IUPAC naming
The organic compound, 4-chloro-3-methylpent-4-ene has been named incorrectly. Draw the implied structure and explain why it is named incorrectly
The compound 2-chloro-4-ethylpentane has been named incorrectly.
(a) Draw the structure implied by the name.
(b) Explain why the given name is incorrect.
(c) Write the correct IUPAC name.
Vitamin A has the structure shown below. Circle and name TWO different functional groups in the Vitamin A molecule above.
Print a table of questions on IUPAC naming that have not yet appeared in the NCEA Exams... complete the table and mark it yourself using the answers provided.
ISOMERS
NCEA PAST EXAM QUESTIONS on structural and geometric isomers
(i) Define the term constitutional (structural) isomer.
(ii) Explain why 1,1-dichloroethene cannot exist as a cis-trans isomer.
(iii) A structural isomer of 1,1-dichloroethene canexist as cis-trans isomers. Draw and name the cis-trans isomers.
The structures of three organic compounds are shown below.
Explain why compound A can exist as geometric (cis and trans) isomers, but compounds B and C cannot. In your answer you should:
• draw the geometric (cis and trans) isomers of compound A in the boxes below
• explain the requirements for geometric (cis and trans) isomers by referring to compounds A, B, and C.
(a) Identify two molecules from the table in (a) that are constitutional (structural) isomers of each other. Justify your choice.
(b) Molecule D can exist as geometric (cis and trans) isomers.
(i) Draw the geometric (cis and trans) isomers for molecule D
(ii) Justify why molecule D can exist as geometric (cis and trans) isomers. Your answer should include:
• an explanation of the requirements for cis and trans isomers
• reference to the structure of molecule D.
1) Four of the structural isomers of C4H10O are alcohols. Draw each of these showing their structural formulae and IUPAC (systematic) names.
2) Can but-1-ene exist as geometric (cis-trans) isomers? Justify your answer, including reference to the requirements for geometric (cis-trans) isomers.
(a) Draw the TWO structural isomers of C2H2Cl2 AND name the isomers.
(b) One of the structural isomers from (b) can exist as geometric isomers (cis-trans).
i) Name the isomer that can exist as geometric isomers.
ii) Draw the geometric isomers of this molecule in the table below.
(c) Discuss why the organic molecule C2H4Cl2 forms structural isomers but does not form geometric isomers whereas the molecule C2H2Cl2 forms both structural AND geometric isomers.
In your answer, you must include:
a description of each type of isomer (geometric or structural)
the characteristics of molecules that form these types of isomer
the structural formulae and functional groups of both C2H4Cl2 AND C2H2Cl2.
i) Only Molecule C can exist as geometric (cis-trans) isomers. Draw the geometric (cis-trans) isomers of Molecule C.
ii) Discuss why Molecule C can exist as geometric (cis-trans) isomers but Molecule A and Molecule B cannot exist as geometric isomers.
In your answer you must include an explanation of what a geometric isomer is.
(a) Identify TWO molecules that are structural isomers of each other using the bold letters from the table above.
(b) i)Identify ONE molecule that can exist as geometric (cis–trans) isomers using the bold letter from the table above.
ii) Draw the cis and trans isomers for your chosen molecule in the boxes below.
iii) Discuss why the molecule you have selected can exist as cis–trans isomers.
Your answer must include:
• an explanation of why cis–trans isomers can exist
• reference to the structure of the selected molecule
(a) i) Draw ALL the structural isomers of alkenes of molecular formula C4H8
ii) One of the isomers of C4H8 can be oxidised with potassium permanganate, KMnO4, to form 2-methyl propan-1,2-diol.
Four different molecules with the molecular formula C5H10 are given below.
(a) Describe why these molecules are structural isomers.
(b) One of the molecules shown above may exist as cis-trans isomers.
i) Identify this molecule using the bold letter from the above table.
ii) Draw the cis and trans isomers of the molecule identified in (i).
(c) Discuss why the molecule you selected in (b) i) may exist as cis-trans isomers, while the other three isomers cannot
Consider the following compounds.
(a) Which compounds are structural isomers? Identify using the bold letters designating the molecules.
(b) Explain why the compounds you have selected are structural isomers.
Structural isomers of the molecular formula C2H2Cl2 are 1,1–dichloroethene and 1,2–dichloroethene.
(a) Circle the compound that can exist as cis-trans isomers: 1,1–dichloroethene or 1,2–dichloroethene
(b) Draw the cis and trans isomers of the compound you circled in (a).
(c) Discuss the requirements for cis-trans isomerism. In your answer include reasons explaining why the structural isomer you selected above can exist as cis-trans isomers while the other structural isomer cannot.
Two alkenes, but–1–ene and but–2–ene, are structural isomers of the compound with the molecular formula, C4H8
(a) Draw and name another structural isomer of the compound, C4H8.
(b) But–2–ene can exist as geometric (cis–trans) isomers, whereas but–1–ene cannot. Explain this difference.
MAJOR AND MINOR PRODUCTS OF ADDITION TO ALKENES
NCEA PAST EXAM QUESTIONS on Major and minor products of addition to alkenes
Explain why Reaction 1 forms only a single organic product, but Reaction 2 forms a mixture of organic products.
Explain why the reactions shown below, are classified as addition reactions.
Explain why compound A is the major product for the reaction above.
For the following reaction:
Describe the product as major or minor and Explain your answer.
The hydrolysis of but-1-ene results in two different products, explain why. In your answer you should include:
• identification of the major and minor products
• an explanation of why there are two possible products
• one of the products will undergo a reaction to form 2-chlorobutane, identify which product and justify your answer
Compare and contrast the reaction of HCl with but-1-ene, CH2 = CH – CH2 – CH3, and but-2-ene, CH3 – CH = CH – CH3.
Your answer must include:
• an explanation of the type of reaction occurring
• equations showing the structural formulae of all reactants and products
• a justification of why major and minor products form with one of these molecules, but not the other.
Discuss the reaction of HCl and Cl2 with but-1-ene, CH3– CH2– CH = CH2.
For each reaction you must include:
• an explanation of the type of reaction occurring
• structural formulae of all organic product(s) formed, including major and minor products, if any.
POLMERISATION OF ALKENES
NCEA PAST EXAM QUESTIONS ON Polymerisation of alkenes
Cling Wrap is a polymer that can be made from the monomer 1,1-dichloroethene. Draw THREE repeating units of the polymer formed.
i) Draw TWO repeating units of the polymer formed in reaction 5
ii) Compare and contrast the polymer formed in reaction 5 to the polymer formed in the first reaction. In your answer you should explain why the polymers formed in these two reactions are different.
i) The molecule tetrafluoroethene, shown below, is the monomer for the polymer commonly known as Teflon.
CF2=CF2Draw TWO repeating units for the Teflon polymer.
ii) The following diagram shows three repeating sections of another polymer.
Draw two repeating units of the polymer formed from but-1-ene
The following diagram shows four repeating sections of the polymer commonly called polypropene. Draw the structural formula of the monomer molecule used to make this polymer.
The molecule
undergoes an addition polymerisation reaction to form a polymer. Draw THREE repeating units for the polymer made from this molecule.
But-2-ene, CH3–CH=CH–CH3, undergoes an addition polymerisation reaction to form a polymer. Draw THREE repeating units for the polymer.
(a) i) The following diagram shows three repeating sections of a common polymer. Draw the structural formula of the monomer molecule used to make this polymer.
ii) The molecule 2-methyl propenoate, shown below, is the monomer for the polymer commonly known as Perspex. Draw the structural formula of the polymer Perspex showing TWO repeating units.
The following diagram shows four repeating sections of the polymer commonly known as PVC. Draw the structural formula for the monomer molecule used to make this polymer.
Complete the table below by drawing the structural formula of the monomer or polymer (showing two repeating units).
Two common polymers are polypropylene and polyvinyl chloride (PVC). A section of each polymer is shown in the table below. Draw the structural formula for the monomer molecule for each polymer.
NCEA PAST EXAM QUESTION: Reactions of haloalkanes
i) For the reaction below
ii) State whether any conditions are required
iii) Describe the type of reaction occurring and explain why it is classified as this type of reaction
Chloroethane, CH3CH2Cl, reacts with aqueous KOH, alcoholic KOH, and with NH3. Compare and contrast the reactions of chloroethane with the three reagents.
In your answer you should include:
• the type of reaction occurring and the reason why it is classified as that type
• the type of functional group formed
• equations showing structural formulae for reactions occurring.
PRIMARY, SECONDARY AND TERTIARY ALCOHOLS
NCEA PAST EXAM QUESTIONS on primary, secondary and tertiary haloalkanes and alcohols
Draw a primary, a secondary, and a tertiary alcohol for the molecule C5H11OH.
Molecule 1 below can be classified as a tertiary alcohol. Molecule 2 can be classified as a tertiary haloalkane.
(a) Describe why both these molecules can be classified as tertiary.
(b) Explain why Molecule 1 and Molecule 2 are not structural isomers of each other. In your answer, you should outline what a structural isomer is, and refer to both molecules.
(c) Draw a structural isomer of Molecule 1
Classify each of the following alcohols as primary, secondary or tertiary and explain your answer for each substance
Vitamin C has the following structure. Classify the –OH groups labelled A and B as primary, secondary or tertiary.
Four alcohols with the same molecular formula are shown in the table below. Complete the table by classifying each alcohol as primary, secondary or tertiary.
Vitamin C has the structure shown below
(a) On the molecule circle the section that is an alkene and would readily react to decolourise bromine water.
(b) Two of the -OH groups in the molecule have been labelled as (A) and (B). Classify these -OH groups as primary, secondary or tertiary alcohol groups.
Sodium carbonate, hydrochloric acid, and sulphuric acid are each added to separate samples of two organic compounds.
The structures of the compounds and the products of any reactions are given in the table below.
Compare and contrast the reactions that do occur between these organic compounds, and the reagents in the table above.
In your answer you should:
• give the structure of the organic products (i) and (ii)
• describe the different types of reactions occurring, and give reasons why they are classified as that type
• identify any specific conditions that are required for the reactions to occur.
When butanoic acid reacts with sodium hydrogen carbonate, NaHCO3, fizzing can be seen during the reaction.
i) What type of reaction is occurring?
ii) Explain why fizzing is observed during the reaction.
iii) Complete the equation below to show the structural formula of the organic product formed.
Give the structural formula of the product formed when ethanoic acid, CH3COOH, reacts with sodium carbonate solution.
Draw and name the product and type of reaction when propanoic acid is reacted with sodium hydroxide solution.
Four separate colourless organic liquids are known to be:
• ethanol
• ethanoic acid
• hex-2-ene
• hexan-1-amine (1-aminohexane).
Write a procedure to identify each of these organic liquids using only the reagents listed below.
• acidified dichromate solution, Cr2O72– / H+(aq)
• bromine water, Br2(aq)
• sodium carbonate solution, Na2CO3(aq).
In your answer, you should:
• identify the test reagents used
• describe any observations that would be made
• identify the type of reaction that occurs
• identify the organic product of any reaction.
You do not need to include equations in your answer.
Five separate colourless organic liquids are known to be:
• pentan-1-ol
• ethanol
• pent-1-ene
• pentane
• ethanamine.
Write a valid method to show how each of these liquids can be identified using only water, litmus paper, and bromine water, Br2(aq).
Your method should allow another student to identify these liquids, and include:
• the reagent used
• any observations made.
You do not need to include equations in your answer.
1) Two bottles containing pent-1-ene, CH3CH2CH2CH=CH2, and hexane, CH3CH2CH2CH2CH2CH3, require identification.
Two reagents, bromine water, Br2, and acidified potassium permanganate, MnO4– / H+, are available.
Evaluate the possible use of BOTH reagents to distinguish between the pent-1-ene and hexane.
In your answer you should include:
• a description of the type of reactions that would occur
• any conditions that would be required
• any observations that would be made
• equations showing the structural formulae of the organic reactant(s) and product(s).
2) State how you could distinguish between aminobutane, CH3CH2CH2CH2NH2, and butanoic acid, CH3CH2CH2COOH, using damp litmus paper.
Give a reason for your answer.
(a) Five colourless organic solutions that have no labels on the their bottles are known to be:
ethanoic acid
aminoethane
ethanol
hexane
hex-1-ene.
Discuss how each of these samples can be identified using only water, red and blue litmus paper, and bromine water.
In your answer, you must include a coherent scheme that would allow another student to follow your method, along with:
the reagent used
observations
chemical equations that show the species reacting and products formed.
Samples of hexane, hex-1-ene and propanoic acid, require identification.
Only two reagents are available: acidified potassium permanganate solution, MnO4– / H+, and sodium carbonate solution, Na2CO3.
Discuss how each of the three samples can be identified using only the reagents above.
Your answer must include:
• a clear description of what you would do
• reagent used
• observations
• equations showing the structural formulae of organic reactant(s) and product(s).
The following substances require identification:
• acidified potassium dichromate
• bromine water
• methanol
• hexane
• hex-1-ene.
Two of these substances are orange in colour, the other three are colourless.
Discuss, using only the five substances, how each could be identified.
Your answer should include:
• a clear description of what you would do
• observations
• equations showing the structural formulae of organic substances for any reactions occurring.
Samples of 1-hexene and ethanoic acid require identification.
Two reagents are available: bromine water and zinc metal.
Discuss the reaction of these two samples with the reagents above.
Your answer must include:
• the reagent used
• observations
• equations showing the structural formulae for any reactions occurring.
Three colourless organic liquids have no labels on the bottles. They are known to be pentanoic acid, pentan–1–ol and pent–1–ene.
(a) Draw structural formulae for these three substances.
Using only aqueous solutions of bromine and potassium permanganate, discuss how a student could identify the liquids.
Your answer should include:
• what is done
• related observations
• conclusions made
• organic products for any reactions occurring.
a) (i) Identify a chemical test to distinguish between propanoic acid and propan-1-ol.
(ii) Describe the test to be carried out and the expected observations for each compound.
(b) The structural formulae for two compounds are given below:
CH3–CH2–CH2–CH2–CH2–CH3 CH2=CH–CH2–CH2–CH2–CH3
hexane hex–1–ene
Both compounds will react with bromine (Br2), but under different conditions. Discuss how the reactions with bromine could be used to distinguish between hexane and hex–1–ene.
In your answer include a description of expected observations, the conditions necessary for a reaction to occur, the type of reaction occurring and explanation for this, relevant equations and names of any products formed.
Chemical tests can be used to distinguish between pairs of compounds. Identify tests to distinguish between butan-1-ol and but-2-ene and
(i) describe the test to be carried out,
(ii) describe the expected observations for the test used,
(iii) clearly explain how the test results can be used to distinguish between them and why the test used is a suitable one.
1) The reactions shown below are all classified as being the same type of reaction.
Compare and contrast these reactions. In your answer you should:
• state whether any conditions are required
• describe the type of reaction occurring and explain why all three reactions are classified as this type of reaction
• explain why two layers form in Reaction One.
2) Sodium carbonate, hydrochloric acid, and sulfuric acid are each added to separate samples of three organic compounds.
The structures of the compounds and the products of any reactions are given in the table below.
Compare and contrast the reactions that do occur between these organic compounds, and the reagents in the table above.
In your answer you should:
• give the structure of the organic products (i) and (ii)
• describe the different types of reactions occurring, and give reasons why they are classified as that type
• identify any specific conditions that are required for the reactions to occur.
3) i)Explain why the reaction shown below, is classified as an elimination reaction.
ii) The reaction belowis also an elimination reaction. Draw the structural formula of the product formed
1) Butan-1-ol can react separately with each of PCl5, Cr2O72–/ H+, and concentrated H2SO4.
For each reaction, your answer should include: the type of reaction occurring and the reason why it is classified as that type
Chloroethane, CH3CH2Cl, reacts with aqueous KOH, alcoholic KOH, and with NH3. Compare and contrast the reactions of chloroethane with the three reagents. In your answer you should include:
• the type of reaction occurring and the reason why it is classified as that type
• the type of functional group formed
• equations showing structural formulae for reactions occurring.
i) The types of reactions below can be described as addition, elimination, or substitution reactions.
Allocate these reaction types to each of the four reactions
1)
CH3–CH2–CH2–OH --> C3H7Cl
Reaction type:
2)
C3H7Cl --> CH3–CH2–CH2–NH2
Reaction type:
3)
CH3–CH2–CH2–OH --> C3H6
Reaction type:
4)
C3H6 --> C3H7Cl
Reaction type:
ii) Compare and contrast the similarities and differences between addition, elimination, and substitution reactions. You should use the examples of the reactions above in your answer
For the following reaction
• Write the structural formula of the organic product formed.
• elimination or addition or oxidation or substitution or hydrolysis or halogenation or acid-base
1) For each of the THREE following reactions:
• Write the name or structural formula of the reactant used.
• State the type of reaction occurring. Choose from acid-base or addition or elimination or hydrolysis or substitution
i)
2) Hydrocarbons can undergo addition and substitution reactions. Compare and contrast addition and substitution reactions. Use the reactions of ethane, CH3– CH3, and ethene, CH2= CH2, with chlorine as your examples in your answer.
Your answer must also include:
• a description of each type of reaction
• conditions for addition and substitution reactions
• equations showing the structural formulae of the organic reactant(s) and product(s).
1) (i) Write the IUPAC name or the structural formula of the product formed.
(ii) State the type of reaction occurring. Choose from the following words: acid-base or addition or elimination or hydrolysis or oxidation or polymerisation or substitution
(a) Ethanol is heated with a catalyst (either concentrated sulfuric acid or aluminium oxide).
(b) Propanoic acid is reacted with sodium hydroxide solution.
(c) Propene is reacted with hydrogen in the presence of a nickel catalyst at 150°C.
2) Compare and contrast the reactions of ethene and ethanol with acidified potassium permanganate. For each reaction you must include:
• observations
• equations showing the structural formulae of the organic reactant and product
• type of reaction occurring.
Some reactions involving organic compounds can be classified as addition or elimination. Use the examples (a) and (b) given below to clearly explain the type of reaction involved:
(i) complete the equation to show the main organic product formed
(ii) use the example to explain why it is classified as that type of reaction.
(a) When HCl reacts with but–1–ene an addition reaction occurs.
(b) When ethanol is heated with concentrated sulphuric acid an elimination reaction occurs.
1.
In Reaction 1, propan-2-ol can be converted to propeneIn Reaction 2, propene can be converted back to propan-2-ol.
Analyse BOTH of these reactions by:
2.describing the reagents and conditions needed for each reaction to occur
identifying each type of reaction and explaining your choice
Ethene, C2H4(g), reacts with aqueous potassium permanganate solution, KMnO4(aq), dilute acid, H2O / H+, and hydrogen bromide, HBr.
Compare and contrast the reactions of ethene gas with each of these three reagents. In your answer, you should:• describe any observations that can be made
• identify, with reasons, the type of reaction ethene undergoes with each reagent
• describe the functional group of the products formed
• include equations showing the structural formulae for the organic compounds for each reaction.
i) When primary alcohols are oxidised by acidified permanganate, MnO4–/ H+, they form carboxylic acids. Draw the primary alcohol that was oxidised to form the carboxylic acid shown.
ii) Permanganate ion, MnO4–, can be used to oxidise alkenes. Draw the product of the following reaction:
Butan-1-ol can be oxidised to form a carboxylic acid.
i) Write the name or formula of a suitable reagent that could be used to carry out the reaction. Include any specific conditions.
ii) Describe the colour change that would be observed.
iii) One of the other alcohol isomers of C4H10O can also be oxidised to form a carboxylic acid. Identify this isomer by name or structural formula: Explain your choice of isomer.
Give the structural formula of the organic product formed when:
(i) Ethanol, C2H5OH, reacts with acidified potassium dichromate solution.
(ii) Ethanoic acid, CH3COOH, reacts with sodium carbonate solution.
(iii) One of the isomers of C4H8 can be oxidised with potassium permanganate, KMnO4, to form 2-methylpropan-1,2-diol. Complete the following equation to show the structural formula of the isomer of C4H8
(iv) 2-methyl propan-1,2-diol can be further oxidised with acidified potassium dichromate, Cr2O72– / H+, to form a compound with molecular formula C4H8O3. The compound C4H8O3 reacts with sodium carbonate solution to form bubbles of carbon dioxide gas. Draw the structural formula of the compound C4H8O3.
1) Complete the following reactions by writing the structural formula of each organic product.
i)ii)
iii)
2) Methylpropene can be formed from methylpropan–2–ol. Identify a reagent that can be used to do this.
Complete the following equations by drawing the structural formula of the organic products in the boxes provided.
i)ii)
b) Reaction (ii)above can also be carried out using one of the reagents shown: H2 / Ptconc. H2SO4 MnO4– / H+
(i) Circle the correct reagent.
(ii) Describe what would be observed when this reaction occurs.
Print out these flowcharts onto paper and stick onto your study wall or toilet door, you need a really clear picture in your head of these reactions. Even better....write and draw out your own flowchart summary.
(i) Complete the scheme above by drawing the structural formulae of the organic compounds A to D.
(ii) Circle the functional group of each of the organic compounds A, B, and C that you have drawn.
(iii) Identify reagents X and Y.
The reactions shown below are all classified as being the same type of reaction.
Compare and contrast these reactions. In your answer you should:
• state whether any conditions are required
• describe the type of reaction occurring and explain why all three reactions are classified as this type
• explain why two layers form in Reaction One.
1) The flow diagram below shows a reaction scheme for the conversion of but-1-ene into but-2-ene.
Use the reaction scheme above to write down:
• the formula of each reagent, including any necessary conditions
• the type of reaction occurring.
2) Butan-1-ol can react separately with each of PCl5, Cr2O72–/ H+, and concentrated H2SO4.
Elaborate on the reactions of butan-1-ol with each of the three reagents.
For each reaction, your answer should include:
• the type of reaction occurring and the reason why it is classified as that type
• the name of the functional group formed in each product
• the structural formula of the organic product.
But-1-ene is used in the reaction sequence shown below.
(i) Draw two repeating units of the polymer, B, formed in Reaction 1.
(ii) Give the name or formula of a suitable reagent in Reaction 4; include any specific conditions required.
(iii) Give the name or formula of a suitable reagent in Reaction 3; include any specific conditions required.
(a) The flow diagram below shows some reactions involving organic substances.
Compound A has a molecular formula C3H8O. It reacts readily with acidified potassium dichromate solution,
(i) Write the structural formula of Compound A.
(ii) Write the structural formulae for Compound B
(iii) Write the name OR formula of Reactant P, Reactant Q, and Reactant R. State any conditions for the reaction to occur
The flow diagram below shows a series of organic reactions.
Complete the diagram by drawing structural formulae and writing IUPAC (systematic) names for the compounds A, B and C (which turns litmus red) and identifying reagent D
An unsaturated compound A, C3H6, reacts with water under acidic conditions to form two new products, B and C. Product B reacts with acidified potassium dichromate solution to form D. Product D reacts with a solution of sodium carbonate producing bubbles of gas.
Write down the structural formula and name for each compound A, B, C and D
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